The present invention relates to an electrolyte-activated alkaline battery, particularly for generating electric energy for the propulsion of underwater systems.
Known batteries of the above type substantially comprise an electrochemical cell; a reservoir containing an anhydrous alkaline compound dissolvable in sea water to form a liquid electrolyte; and a system for forming and circulating the liquid electrolyte between the reservoir and the electrochemical cell.
In actual use, said system communicates with the outside environment (i.e. the sea) via a sea water inlet conduit, and via an outlet conduit located at the outlet of a gas separator and which, among other functions, provides for expelling the gas contained inside the reservoir when this is filled, for expelling the gas (hydrogen) produced during the battery discharge reaction, and for expelling the electrolyte when draining or deactivating the battery.
The inlet and outlet conduits normally present closure members for ensuring airtight sealing during storage of the battery, and which are detached when the system is launched.
For this purpose, various solutions are adopted, and the closure members may consist, for example, of diaphragms pierced by external pressure at immersion or by explosive devices; or plugs which are expelled outwards.
Known batteries of the type briefly described above present several drawbacks, mainly due to the design and opening method of the closure members.
In the case of diaphragms pierced at a predetermined breakthrough pressure, these fail to provide for adapting to different service conditions, and in particular to different launch depths corresponding to different hydrostatic pressures. Conversely, in the case of outwardly expelled closure members, expulsion may be impeded by the hydrostatic pressure to which the members are subjected and which obviously increases alongside an increase in immersion depth. This therefore limits application of the battery, on account of the impossibility of expelling the closure members at the depths involved, for example, in the event the system is launched from a submarine.
Moreover, outward expulsion of the closure members or fragments of them may result in damage or jamming of the launching equipment, and in abortion of the launching operation; while explosive devices are unsatisfactory on account of the noise factor involved.